This project is divided into two parts: 1) control of specific lymphokine (i.e. interferon gamma) gene expression; and 2) analysis of T cell receptor DNA structure during the growth and differentiation of immune effector cells (i.e. T cells, LGL, B cells and monocytes). 1. We have identified specific regions of human interferon gamma genomic DNA which can significantly effect the expression of this gene by transfecting DNA constructs containing IFN-gamma genomic DNA linked to chloramphenicol acetyltransferase into a variety of murine cell lines. At least two regions of the DNA which contain enhancer elements have been identified. In addition, we have observed that the DNA sequences in the first intron of the gene are required for mRNA expression in a murine B cell line and may be involved in cellular responses to calcium mobilization. 2. Comparison of the methylation pattern of the T cell receptor beta chain gene (T beta) in different lymphoid populations has revealed additional distinct differences between these cell populations. Hypomethylation of the gene was found to correlate with gene expression and to be highest in T cells and lowest in B cells and monocytes. Specific differences in methylation patterns were noted when T cell DNA was compared to LGL DNA and B cell DNA was compared to monocyte DNA. In addition, the T cell receptor beta chain gene in immature mouse thymocyte (dlyl) DNA was found to be more highly methylated than the DNA isolated from CD4+ or CD8+ thymocytes.